1. Field of the Invention
The present invention relates to data acquisition and logging systems for subsurface resource drilling and more particularly relates to generating data for a reaming operation.
2. Related Art
The exploration for subsurface resources such as hydrocarbons including oil and gas, minerals and water, typically requires various techniques for determining the characteristics of geological formations. Many characteristics, such as the hydrocarbon volume, resistivity, porosity, lithology, and permeability of a formation, may be deduced from certain measurable quantities associated with the geological formations. Drilling for subsurface resources to determine the characteristics of the geological formations is a well known technique. A drilling rig is typically deployed to drill a well for exploring the subsurface resources.
The data acquisition and logging system is typically used to acquire information describing the well characteristics. The information may be acquired in real-time by a sensor equipped drilling tool and communicated to a back-end portion of the logging system for performing additional processing. The term xe2x80x9creal-timexe2x80x9d data, as used herein, includes data acquired and recorded while the drilling tool is in the well, and transmitted to the surface shortly after being acquired. Transmission typically occurs and is completed substantially while the drilling tool is in the well, and is typically by a method with limited bandwidth, such as mud-pulse telemetry. It is well known that only a subset of the recorded data can be transmitted as real-time data because of the limited data transfer rates of down-hole telemetry systems. This reduces the number of channels, the sample interval, or both, in the real-time data.
In many cases, information may be acquired in a xe2x80x9crecorded modexe2x80x9d by the drilling tool, according to which data is acquired and stored in a memory device of the drilling tool. The recorded data may be subsequently retrieved from the memory when the drilling tool is brought to the surface. The term xe2x80x9crecorded data,xe2x80x9d as used herein, includes data stored in the memory of the drilling tool while the drilling tool is in the well. Thus, recorded data are distinct from real-time data.
It is well known that the drilling rig can be operated in several modes such as drilling, reaming, and tripping to penetrate the geological formations. For example, during the drilling operation the drilling bit is described as being xe2x80x9con-bottomxe2x80x9d. (It should be understood that the term xe2x80x9cdrillingxe2x80x9d has a rather specific meaning when used in the context of operating in a xe2x80x9cdrilling mode,xe2x80x9d as just described. The term xe2x80x98drillingxe2x80x9d may also be used in a more general sense, such as in the context of xe2x80x9cdrilling the wellxe2x80x9d or xe2x80x9cmeasurement while drillingxe2x80x9d (xe2x80x9cMWDxe2x80x9d), which are mentioned herein below.) In the reaming operation the drilling tool is rotating but its bit is xe2x80x9coff-bottomxe2x80x9d (i.e. not drilling), regardless of whether the drilling tool is moving up or down. In the tripping mode the drilling tool is being lowered into or pulled out of the oil well, but generally is not rotating. For the purposes of this invention, xe2x80x9creamingxe2x80x9d covers both tripping and reaming.
A drilling rig is typically capable of operating only in one mode at a given instant. For example, the rig cannot be reaming and drilling at the same time. Consequently, when the rig is reaming toward bottom, the rig mode automatically changes to the drilling mode as soon as the bit touches the bottom of the hole. Therefore, in data acquisition terms, data acquired in a reaming operation is not xe2x80x9con-bottomxe2x80x9d.
It should be understood that data acquired in well logging may be acquired over a period of days, weeks or even months and is therefore voluminous. Consequently, the well logging system automatically processes data as it is acquired to make the data more accessible. Typically, a set of data of particular interest is identified by the well logging system by automatically generating a data file for it. Moreover, existing well logging systems typically automatically generate real-time data files only for real-time data acquired on-bottom. In some cases, existing systems can also generate a real-time, xe2x80x9coff-bottomxe2x80x9d data file, such as a reaming data file (also sometimes referred to as a xe2x80x9cream sectionxe2x80x9d), provided that the system is configured to do so prior to acquiring the data. For recorded-mode data, well logging system flexibility is conventionally even more limited. It should therefore be appreciated that the need exists to create ream section data for a selected depth range after acquiring real-time data without requiring extensive manual data manipulation or repositioning. Furthermore, it would be desirable to facilitate automatic creation of accessible ream section data from both real-time and recorded mode data.
The foregoing need is addressed by the present invention. According to one form of the invention, a method for generating a depth-indexed data structure for a reaming operation includes receiving, by a software process, i) well logging data that includes time-indexed data and surface measurement data for a drilling rig, ii) a selection identifying a depth range for the reaming operation by the drilling rig, and iii) values for a certain parameter, the values indicating respective operating modes for the drilling rig. Then the software process extracts, responsive to the selected depth range and one of the values of the parameter, a section from the well logging data within the selected depth range, and generates from the section the depth-indexed data structure for the reaming operationxe2x80x94.
In another aspect, the parameter is user-selected. As an alternate, the parameter is program selected.
In an alternative, the parameter is included in the received well logging data.
In still another alternative, the parameter is included in the received well logging data but changeable responsive to a user-selection.
Other forms, as well as additional aspects, objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings.